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Abstract

The cerebellum is a highly connected structure, and its involvement in sleep – which is a dynamic process that is modulated by a complex set of neural systems – can come about through a number of neural pathways. We conducted two studies aimed at furthering our understanding of cerebellar involvement in sleep behavior and physiology, as well as measuring the impact of poor sleep on mood and cognition in patients with cerebellar degeneration. First, by means of an online battery including measures of sleep and neuropsychiatric function, we collected data from 176 patients with cerebellar ataxia. We found strong evidence of poor subjective sleep quality, symptoms of movement-related sleep disorders, and excessive daytime sleepiness in this sample. Importantly, poor subjective sleep was associated with both diminished perceptions of cognitive abilities and depression symptomatology. Second, in order to determine whether the benefit of sleep on declarative associative learning, previously observed in healthy controls, was affected by cerebellar degeneration, we compared overnight changes in performance on a word-pair association task between patients with pure cerebellar syndrome and matched-controls. By means of polysomnography recordings, we demonstrated significantly greater fragmentation of sleep and periodic limb movement indices in patients relative to controls. Although patients demonstrated impaired learning of the word-pair association task – which was significantly correlated with sleep fragmentation – there were no differences between patients and controls with respect to overnight change in accuracy on the word-pair task. Taken together, these findings suggest that inefficient sleep and the presence of sleep disorders in patients with cerebellar ataxia might exacerbate deficits in certain non-motor domains, while other processes – namely those associated with sleep-dependent declarative memory consolidation – remain intact.